There MUST be some among us who've been aware this was out there. Like Bill Ricca perhaps? Or Scott Duff? No, unless it was among tools marked for the M1 I wouldn't know and then it would take time to guess. If you didn't know about the sight seal it would be more difficult to imagine too.

If I recall that image is from the Rock Island publication. The funny thing about Rock Island was the organization made many tools that it used and were never distributed by Ordnance. Some of the tools were redesigned and manufactured for the system, others never existed outside of Rock Island.